Alarm system with timed exit circuit means

ABSTRACT

An intruder-activated alarm system operating pursuant to the McCullough loop principle. The system includes a protected circuit incorporating an exit means-controlled switch. Arming means for the protected circuit includes a delay circuit for suspending activation of the protected circuit for a predetermined period. Subsequent to such period, opening and closing of said exit means-controlled switch causes a motor to successively cycle and drive a coded transmitter which sends two rounds of signals to a central office. Subsequent disruption of the protected circuit causes further operation of said motor, which in turn effects transmission of alarm signals to said central office.

United States Patent Guthart 1 Feb. 26, 1974 1 1 ALARM SYSTEM WITHTIME!) EXIT 3,510,863 5/1970 MCBI'IUI] 340/276 3,286,250 11/1966'Icilclhaum 1. 340/276 CIRCUIT MEANS Primary Examiner-John W. CaldwellAssistant ExaminerScott F. Partridge Attorney, Agent, or Firm-Sommers &Sommers [57] ABSTRACT An intruder-activated alarm system operating pursuant to the McCullough loop principle. The system includes a protectedcircuit incorporating an exit meanscontrolled switch. Arming means forthe protected circuit includes a delay circuit for suspending activationof the protected circuit for a predetermined period. Subsequent to suchperiod, opening and closing of said exit means-controlled switch causesa motor to successively cycle and drive a coded transmitter which sendstwo rounds of signals to a central office, Subsequent disruption of theprotected circuit causes further operation of said motor, which in turneffects transmission of alarm signals to said central office.

7 Claims, 2 Drawing Figures [75] Inventor: Leo (Iulharl, ()ld Wcsthury,NY.

[73] Assignee: AIa rm Device Manufacturing W Company, a division ofPittway Corporation, Syosset, NY.

[22] Filed: Feb. 7, 1972 [21] Appl. No.: 224,186

[52] US. Cl. 340/409, 340/276 [51] Int. Cl. G08b 13/08, G08b 29/00 [58]Field of Search... 340/274, 276, 293, 215, 309, 340/409, 214

[56] References Cited UNITED STATES PATENTS 3,484,771 12/1969 Falck340/215 X 3,534,350 10/1970 Sellinger... 340/276 X 3,548,401 12/1970Guthart i 340/276 X 2,783,462 2/1957 Chase i i i 1 340/276 3,636,5461/1972 Lomonaco 340/276 TRANSMITTER ALARM SYSTEM WITH TIMED EXIT CIRCUITMEANS BACKGROUND OF INVENTION This invention relates generally tointruder-activated alarm systems, and more specifically relates tocentral station alarm systems operating on the McCullough loopprinciple.

In US. Pat. No. 3,548,401, issued on Dec. 15, 1970, to Leo A. Guthart,which patent is assigned to the assignee of the instant application, ahighly effective alarm system is disclosed operating on the so-calledMcCullough loop principle. Pursuant to this principle a plurality ofsubscribers share a common telephone line (or a radio frequency band orthe like) and are differentiated by the nature of the code transmittedat the subscribers station. The said patent in particular, disclosed asystem wherein simplification in supervisory functions is enabled viause of an arrangement wherein an exit means controlled switch activatesa motor for driving a coded transmitter which provides signals to thecentral office. In accordance with said disclosure a subscriberinitially arms the system, and then proceeds to leave the premises. Whenthe exit door of the premises is opened one round of information istransmitted to the central office; when the said door is closed a secondround of information is transmitted; subsequently interruptions in theprotected circuit e.g., by opening protected windows, doors or the likewill transmit three rounds of signals to the central office, therebypresumably signaling entry of an intruder into the protected zone.

Unfortunately the system as set forth in the prior paragraph, has insome instances functioned in a less than ideal fashion. In particularwith certain installations, there is a possibility that an error canoccur as the proprietor of the premises walks toward the exit doorfollowing the initial arming of the alarm system. Such accident duringclosing can occur if interior protection devices like photoelectricbeams or motion detectors are used. Once a subscriber arms a system thusprovided, a closing signal is sent to the central station the very nexttime that the protective circuit is interrupted. If, accordingly, thesubscriber should accidentally interrupt a photoelectric or motiondetector on his way out, there is a possibility that the two closingrounds will be sent at that time. When the subscriber finally thenreaches the door, the transmitter will interpret that as an alarmsignal, rather than a closing signal. The net result of the accidentaldisturbance is that the subscriber has left the premises and the systemhas already reported a closing and an alarm, and is no longer armed.This means that the alarm company must come to the premises and resetthe unit. Aside from the obvious inefficiency and costs involved in suchresetting operations, it may be observed that false alarms of this typetend to impair confidence in the alarm system and act as a psychologicaldeterrent to effective use thereof.

In an effort to eliminate the aforesaid problem, various schemes have inthe past been proposed, intended to delay sending of signals subsequentto arming of the alarm. These have commonly taken the form of relativelycrude mechanical delay mechanisms placed directly onto the protectiondevices themselves. For example. an installation company might place atime delay on a motion detector in an attempt to hold out from thetransmitter any interruptions of the motion detector. This type ofdelay, however, is unsupervised and runs the risk that the delay willstay on and the motion detector will be inoperative for the entirenight.

In accordance with the foregoing, it may be regarded as an object of thepresent invention, to provide an intruder-activated alarm systemoperating on the McCullough loop principle, which includes featurespreventing accidental sending of alarm signals during the closingoperation.

It is a further object of the invention, to provide anintruder-activated alarm system of the McCullough type, wherein armingof the system may be followed for a limited period by any number ofaccidental disruptions of the protected circuit without-causing the sending of closing signals, whereby accidental indication of an alarmcondition is prevented during the closing operation.

It is an additional object of the invention, to provide anintruder-activated alarm system of the McCullough variety, includingdependable electrical means for delaying sending of closing or alarmsignals following arming of the system, which means, further, act toalert the central station should the subscriber not close in a propermanner.

SUMMARY OF INVENTION Now in accordance with the present invention, theforegoing objects, and others as will become apparent in the course ofthe ensuing specification, are achieved by incorporating a timed exitcircuit into the arrangement set forth in the Guthart patent previouslyalluded to. The said circuit functions in combination with the basicsystem as to prevent subscribers from sending accidental closing signalson their way out from the protected premises at the end of the day. Inparticular the circuit acts to place a hold of approximately 60 secondson the protective circuit once the transmitter is armed. During thishold period the subscriber can disturb the protective circuit any numberof times and no closing signals will be sent. At the end of the 60seconds hold, if the protective circuit is closed and there has been atleast one opening and closing during the period, two consecutive closingrounds will be sent. On the other hand, if the protective circuit isleft open at the end of the 60 seconds, only one round will be sent,alerting the central station that the subscriber has not closedproperly. An intrusion or re-entry will cause a three round alarm signalwith no delay.

BRIEF DESCRIPTION OF DRAWING The invention is diagrammaticallyillustrated, by way of example, in the drawing appended hereto, whereinsimilar reference characters indicate like parts, in which:

FIGS. 1 and 2 taken together are a schematic diagram of a circuit inaccordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENT In FIGS. 1 and 2 a schematic diagramappears, setting forth an alarm system in accordance with the presentinvention. The system is seen to include generally a protected circuit 3(FIG. 2) and an alarm circuit 5 (FIG. 1). Terminals 7, 9, l1 and 13 arecommon to the circuits 3 and 5 whereby, as will be seen, variousfunctions are enabled, depending upon the position of movable contact15. Thus when contact 15 overlies terminal 7 the circuit 1 is in an on"state; similarly at terminal 9 the circuit is in a test" position; atterminal 11, in a bell test position; and at terminal 13 the circuit isof Protected circuit 3 is seen to include a pair of terminals 17, 19which are connected to a supervisory battery, not explicitly shown. Inseries therewith are the coil 21 for a solonoid switch 23 located inalarm circuit 5, an ammeter 25, and access controlled switches 27, 29.The latter two elements are taken to be two in number merely by way ofexample. In practice a larger number of such switches could be soutilized. It may furthermore, for purposes of illustration, be assumedthat switch 27 is a normally closed window operated unit, and switch 29a normally closed switch that is opened upon opening of the door to thepremises sought to be protected.

Alarm circuit is seen to be centered upon an electric motor 31 ofconventional design, which for each revolution drives a transmitter 33,also conventional. For each revolution of the said motor transmitter 33sends out a coded message, which may be transmitted by land lines,telephone, radio link or so forth, to a central monitoring station. Suchfacet of the invention is wcllknown in the art and need not be furtherdescribed herein.

Motor 31 also drives a switch. in a preferred form of the invention, theswitch is an intermittently driven wafer stepping switch 35 driven fromthe motor 31 by reduction gearing or the like. The switch and motorarrangement is essentially identical to similar elements disclosed inthe aforementioned Guthart patent. Switch 35 is provided with contactsequally spaced apart circumferentially, and a rotor 37 having an arcuatelobe 39 of an extentjust short of spanning any two adjacent contacts.For purposes of description each contact in the Figure is provided witha number designation running serially from 1 to 10. The normal restposition of switch 35 is, as shown, with the lobe 39 midway ofcontact 1. The lobe 39 is at all times connected to a wiper at 41.

In order to understand the operation of the present system, let it beassumed that initially the system is activated or armed" by placing armin the on position, that is by moving arm 15 to a position upon contact7. Under such conditions coil 21 carries current and in consequenceswitch 23 is placed in the on position shown in the Figure by the dottedline 43', wherein the arm 43 of such switch electrically engages contact46. At the same time it will be seen that with contact 7 closed in thealarm circuit 5, the solonoid coil 47 is series therewith is connectedto the positive side 49 of a battery 51 in the said circuit; inconsequence arm 53 associated with coil 47 is displaced to the closedposition shown wherein it engages contact 55; the return circuit fromcoil 47 includes diode 48, lead 57, contact 7, lead 59, thence contact 1lobe 39 and contact 6 at switch 35, and lead 61 back to the negativeside 63 of battery 51.

Under the conditions set forth above negative terminal 63 of battery 51is also coupled through contact 55, diode D1 and lead 67 to the gatecircuit of SCR 73. SCR 73 is normally non-conductive but upon firingwill provide a conductive path through leads 75 and 77 to one side 79 ofmotor 31, thereby enabling motor 31 upon application of a potential toits alternate lead 81.

Regarding now terminal 81 of motor 31, it will be appreciated thatpositive terminal 49 of battery 51 is connected to such terminal vialead 81 and thence via depending upon the position of arm 83 one of tworoutes. With arm 83 contacting point 85, as shown, the route is throughresistor 87 and diode 89 and thence the pair of transistors 91, 93, theoutput from the latter proceeding via lead 95 to terminal 81. This routefor enablement of motor 31 is a delay route, the time delay dependingspecifically upon the values of resistor 87 and capacitor 97, butgenerally being about 60 seconds. Alternatively it will be noted thatthe arm 83 may be positioned on contact 86 in which case no delay inenablement of motor 81 occurs.

Assume that at some time during the timing out of the 60 second delayperiod, switch 23 is opened and closed, i.e., that arm 43 is displacedback and forth from its dotted line position. Upon such occuring a pulseis coupled from capacitor through resistors 69, 68, and capacitor 71 tothe gate circuit of SCR 73, firing the latter to conduction. A path isthereby enabled through SCR 73, leads and 77, to one side 79 of motor31. Assuming therefore that arm 83 is in its delay position it will beclear that a potential is applied to the motor at the end of the delayperiod. The motor 31 then moves rotor 37 from contact I to 2 and a roundof signals is sent as transmitter 33 is activated. Upon lobe 39 reachingcontact 3, it is seen that terminal 79 of the motor is still inelectrical contact with the negative side of battery 51, now via lead 99from contact 2; thus a second round of signals is immediately sent fromtransmitter 33, after which the rotor comes to rest with lobe 39 restingon contact 3. Since arm 23 is in its lower position i.e., upon contact46, no further movement of rotor 37 ensues. It will further be evidentthat thereafter, if intrusion, say at door switch 29 (or otheraccess-controlled switch such as switch 27) occurs, arm 43 is displacedto contact 45, whereupon lobe 39 activates motor 31 through theconnection of lead 75. The lobe 39 thence is displaced to contact 4,which is still connected (by lead 99) to motor 31, whereupon a secondround of signals is sent; finally lobe 39 is displaced from contact 5 inconsequence of the conductive path through lead 101, SCR 73 and lead 75and a third round of signals is thereby provided from transmitter 33.

Let it be supposed that, as sometimes happens, a closing is improperlyeffected as the proprietor departs from the protected premises. Undersuch conditions arm 43 is left in an open position, that is upon contact45. Upon such occuring it will clear that the lobe 37 will only rotateso far as contact 2, since contact 3 can effect no conductive path viaarm 43. Therefore only one round of signals is generated by transmitter33, in consequence of which it is made known to the central monitoringstation that an improper closing has occurred at the premises.

In order to provide a local indicator of alarm conditions, it is seenthat a bell 109 is provided. One side of bell 109 is connected toterminal 111 and thus to positive terminal 49 of battery 51. The otherside of the bell is connected to a terminal 113 and thence via lead 115to contact 117. As soon as current in coil 47 is disrupted for anyreason, arm 53 moves to contact 117, and upon lobe 39 reaching contact1, the local bell alarm is sounded.

' pended hereto.

I claim: 1. An intruder-activated alarm system for premises, comprisingin combination:

a. a protected circuit and an alarm circuit at said premises;

b. a code transmitter;

c. a motor for driving said transmitter;

d. a switching system contained in said protected circuit, said systemincluding an exit means controlled switch;

e. arming means, for activating said circuits;

f. power supply means for said system;

g. delay means for suspending activation of said alarm circuit for apredetermined period following arming thereof, comprising a delaycircuit interposed between said power supply means and a first side ofsaid motor, said delay circuit being responsive to said arming bydelaying application of potential to said motor for said predeterminedperiod;

h. means initiated upon an opening and closing of said exit meanscontrolled switch during said predetermined delay period, to enable apotential to the second side of said motor to operate said transmitterfor a predetermined operation after running of said delay period,whereby to provide a signal indicative of proper closing by authorizedpersons 6 departing said premises; and

i. means operated upon subsequent opening of said protected circuit tofurther operate said motor and said transmitter for a predeterminedoperation, to provide an alarm indication.

2. A system in accordance with claim 1, wherein said delay circuitcomprises a pair of normally nonconductive transistor switches activatedby an RC delay circuit.

3. A system in accordance with claim 1, further in-' cluding means toselectively shunt said delay circuit, whereby said system may optionallybe operated without delay following arming thereof.

4. A system in accordance with claim 1, further including means operableupon said access-operated switch being left in an open conditionfollowing said delay period, to activate said transmitter for apredetermined operation, whereby signals indicative of a faulty closingat said premises are sent to a monitoring point.

5. A system in accordance with claim 1, wherein said means causing saidmotor to operate upon opening and closing of said access-operated switchduring said delay period, includes a normally non-conductive SCRconnected between one terminal of said motor and said power supply, thegate circuit of said SCR being connected to fire said SCR to conductionupon said opening and closing operation.

6. A system in accordance with claim 4, further including local alarmmeans and means to activate said local alarm means upon opening of saidprotected circuit subsequent to said delay period.

7. A system in accordance with claim 5, further including selectivelyactivatable circuit means for testing said local alarm and protectedcircuits.

1. An intruder-activated alarm system for premises, comprising incombination: a. a protected circuit and an alarm circuit at saidpremises; b. a code transmitter; c. a motor for driving saidtransmitter; d. a switching system contained in said protected circuit,said system including an exit means controlled switch; e. arming means,for activating said circuits; f. power supply means for said system; g.delay means for suspending activation of said alarm circuit for apredetermineD period following arming thereof, comprising a delaycircuit interposed between said power supply means and a first side ofsaid motor, said delay circuit being responsive to said arming bydelaying application of potential to said motor for said predeterminedperiod; h. means initiated upon an opening and closing of said exitmeans controlled switch during said predetermined delay period, toenable a potential to the second side of said motor to operate saidtransmitter for a predetermined operation after running of said delayperiod, whereby to provide a signal indicative of proper closing byauthorized persons departing said premises; and i. means operated uponsubsequent opening of said protected circuit to further operate saidmotor and said transmitter for a predetermined operation, to provide analarm indication.
 2. A system in accordance with claim 1, wherein saiddelay circuit comprises a pair of normally non-conductive transistorswitches activated by an RC delay circuit.
 3. A system in accordancewith claim 1, further including means to selectively shunt said delaycircuit, whereby said system may optionally be operated without delayfollowing arming thereof.
 4. A system in accordance with claim 1,further including means operable upon said access-operated switch beingleft in an open condition following said delay period, to activate saidtransmitter for a predetermined operation, whereby signals indicative ofa faulty closing at said premises are sent to a monitoring point.
 5. Asystem in accordance with claim 1, wherein said means causing said motorto operate upon opening and closing of said access-operated switchduring said delay period, includes a normally non-conductive SCRconnected between one terminal of said motor and said power supply, thegate circuit of said SCR being connected to fire said SCR to conductionupon said opening and closing operation.
 6. A system in accordance withclaim 4, further including local alarm means and means to activate saidlocal alarm means upon opening of said protected circuit subsequent tosaid delay period.
 7. A system in accordance with claim 5, furtherincluding selectively activatable circuit means for testing said localalarm and protected circuits.